1. Field of the Invention
The present invention relates to a method of multi-potential level switching operation voltage of CPU power management, especially used in a N-divisions algorithm to switch CPU operation voltage for solving unstable system during the multi-potential level switching operation voltage of CPU.
2. Description of the Prior Art
In market, traditional computer system with multi-potential level switching operation voltage adopted CPU is according to real situation to switch both CPU operation voltage and working frequency for achieving stable job and electric energy saving. This technology is called CPU power management. When CPU is executing a lot of programs and in full loading, it switches higher CPU operation voltage and frequency. Otherwise, when CPU is executing few programs and not in heave loading, it switches to lower CPU operation voltage and frequency.
According to conventional CPU power management, switching CPU power management comprises a power supply to provide a steady voltage for voltage regulator, as show in FIG. 1. The voltage regulator 10 provides a steady voltage 12 via signal line of VCPU# to CPU. The specification of general IBM computers, especially notebook computers, the power management of CPU 12 switches to lower work voltage while the CPU 12 is standby and if the CPU is active within full loading switched to higher work voltage, so as to achieve electric energy saving. For achieving object as above, the CPU 12 inform the voltage regulator 10 via signal line of CPU_VID#, then the voltage regulator 10 provide the operation voltage what CPU 12 need by VCPU# signal line.
Besides, the working mode of voltage regulator 10 in normal computers, shall be designed to reset the system when the operation voltage value divergence or the system is unstable for stabilizing the circuit system. The voltage regulator 10 drop down POWER_GOOD# signal of south bridge chip 14 connecting the system while south bridge chip 14 received the POWER_GOOD# was dropped down, CPU_RESET# signal was dropped down, simultaneity, then the CPU 12 reset.
The prior known to switch CPU operation voltage in CPU power management not asked voltage regulator 10 to reset the system is controlled by hardware. In circuit design, for solving the problem of voltage regulator 16 rests not only upgrades the specification of voltage regulator for supporting IMVP (Intel Mobile Voltage Positioning) and also has to install a GCL controller 18 between CPU and voltage regulator with IMVP additionally for stable the system. Referring to FIG. 2, while CPU_VID# signal of CPU 12 switching to higher voltage, CPU informs to IMVP voltage regulator 16 by the CPU_VID# signal line and voltage regulator 16 provides a stable voltage via Vgate# signal line to GCL controller 18. The GCL controller 18 informs to CPU 12 by POWERGOOD_CPU# signal line that variable voltage is in normal switch range. If the CPU_VID# signal does not change, the IMVP voltage regulator 16 change huge means the power is out of order. It should be reset the CPU 12 by south bridge chip 14.
As above described prior technology is according to hardware device, the hardware device control the CPU has limited the usage and generated the extra cost. In PC market, cost is very important. Decreasing the number of ICs in use will be cost down and less IC chip layoff on circuit, furthermore decreasing the PC main board cost. Thereby, the present invention provides a method for switching the CPU operation voltage used in N-division algorithm by software to solve the problems as above described.